Rapid forearc spreading between 130 and 120Ma: Evidence from geochronology and geochemistry of the Xigaze ophiolite, southern Tibet

Lower Cretaceous Xigaze ophiolites formed in the Gangdese forearc: Evidence from paleomagnetism, sediment provenance, and stratigraphy

“…These ages are consistent with previous radiolarian biostratigraphic studies and detrital zircon U-Pb dating results from the Xigaze Group turbiditic sandstones (Wu et al, 2010), and overlap with the ages of the magmatic units of the Xigaze ophiolite of ∼130-120 Ma (e.g., Guilmette et al, 2009;Dai et al, 2013). The radiolarites of the Chongdui section that overlie the pillow lavas, interfinger with sandy turbidites that were previously ascribed to the Xigaze forearc (e.g., Wu et al, 2010).…”

“…1b,c). Based on zircon U-Pb and hornblende 40 Ar/ 39 Ar dating, the reported age of the magmatic ophiolite crust is 123-128 Ma (e.g., Guilmette et al, 2009;Dai et al, 2013). This is consistent with a Barremian to Albian age inferred from radiolarian biostratigraphy of the ophiolite's cover sediments Ziabrev et al, 2003).…”

“…Geochemical studies have indicated a variety of compositions and geochemically inferred geodynamic settings in the Yarlung Zangbo ophiolite belt (Hébert et al, 2012). Our paleomagnetic results, as well as the stratigraphic and sedimentary evolution of the Xigaze ophiolite's cover presented in An et al (2014), suggest that this geochemical complexity should somehow have evolved during the extensional fragmentation of the Gangdese forearc that culminated in the formation of the Xigaze ophiolite, and led to their dismemberment (see also Dai et al, 2013; Maffione et al, submitted for publication).…”

Melt evolution of upper mantle peridotites and mafic dikes in the northern ophiolite belt of the western Yarlung Zangbo suture zone (southern Tibet)

“…Mafic-ultramafic rock assemblages in different ophiolite massifs and mélanges along the YZSZ have been studied extensively during the past 30 years (i.e., Miller et al, 2003;Liu et al, 2010;Bezard et al, 2011;Dai et al, 2011;Guilmette et al, 2012;Hébert et al, 2012;Guo et al, 2015;Li et al, 2015;Niu et al, 2015;Lian et al, 2016Lian et al, , 2017Feng et al, 2017). Geodynamic models explaining the geochemical evolution of the YZSZ ophiolites, their tectonic origin of magmatic construction within a broad Neotethys oceanic realm, and the paleography of this Mesozoic-Cenozoic ocean basin vary significantly Dai et al, 2013;C. Liu et al, 2014;Liu et al, 2015a;Gong et al, 2016;Lian et al, 2016;Xiong et al, 2016).…”

The Zhaheba ophiolite complex in Eastern Junggar (NW China): Long lived supra-subduction zone ocean crust formation and its implications for the tectonic evolution in southern Altaids

“…Yarlung Zangbo ophiolite in Tibet (Dai et al, 2013). Some of these ophiolites display a socalled "complete" pseudostratigraphy that includes pelagic sedimentary rocks, volcanic A C C E P T E D M A N U S C R I P T…”